Around 1970, it was believed that the Loop Current exhibited an annual cycle in which the Loop feature extended farther to the north during the summer. Further study over the past few decades, however, has shown that the extension to the north (and the shedding of eddies) does not have a significant annual cycle.

The Loop Current and its eddies may be detected by measuring sea surface level. Sea surface level of both the Eddies and the Loop on September 21, 2005 was up to 60 centimetres (24 in) higher than surrounding water, indicating a deep area of warm water beneath them.[1]